Radio frequency identification (RFID) systems frequently use auxiliary systems to detect the presence or approach of objects through the desired read zone. The auxiliary systems might be light curtains, passive infrared devices, ultrasonic motion detectors, etc. Applications include detecting forklifts or hand trucks passing through RFID portals to load and unload cargo in a shipping and receiving environment, or detecting people or shopping carts moving through an entry/exit gate in an retail electronic article surveillance (EAS) system. These auxiliary object detection systems add to the cost of the RFID installation and decrease the reliability of the overall system.